Bag with interrupted longitudinal seam



April 6, 1963 D. HORTON BAG WITH INTERRUPTED LONGITUDINAL SEAM FiledApril 25, 1962 INVENTOR. DONALD HORTON EEG-3 4 ATTORNEY United StatesPatent Ofi 3,085,737 Patented Apr. 16, 1963 ice 3,085,737 BAG WITHINTERRUPTED LONGITUDINAL SEAM Donald Horton, Wycofl, N.J., assignor toOlin Mathieson Chemical Corporation, a corporation of Virginia FiledApr. 25, 1962, Ser. No. 190,018 7 Claims. (Cl. 229-55) The presentinvention relates to bag or sack structures and in particular relates tobags or sacks which are useful for packaging bulk material such asflour, cement and similar powdery or fined granular material.

A particular feature of the invention is the provision of a novel ventedsack structure which provides a continuous outlet for entrapped air thatmust be displaced while the bag is being filled with bulk material.

An additional feature of the invention is the provision of a sack forreceiving or packaging 'bulk material having a novel seam structure.

A further feature of the invention is the provision of a multi-wallkraft paper sack of the type having a single opening through which bulkmaterial is introduced and having separate and independent vent meansoperative to release entrapped air continuously while the sack is beingfilled.

A further feature of the invention is the provision of a sack structurehaving a single opening for introducing bulk material disposed in afirst location and having a separate and independent vent structurelocated in a second remote location.

A further feature of the present invention is the provision of a papersack structure having a longitudinal seam provided with spaced securingmeans thereby effecting a plurality of discrete openings providingcommunication from the interior of the sack to the atmosphere throughthe seam.

A further feature of the invention is the provision of a novelmulti-wall sack structure in which each wall is defined by an individualsack having a longitudinal lap seam individual thereto, the lap seamindividual to each sack being fastened intermittently or at spacedpoints along the seam.

A vented sack structure embracing certain principles of the presentinvention and useful for packaging bulk materials such as flour, cementand the like may comprise a body portion fabricated of packagingmaterial having a generally tubular structure including a longitudinallap seam, said lap seam defining overlapping margins of said packagingmaterial secured intermittently to provide spaced regions along said lapseam wherein said overlapping margins are fixed against relative motionwith intervening spaced regions wherein the overlapped margins arefreely separable and susceptible of relative motion.

Other features and advantages of the present invention will become moreapparent from an examination of the succeeding specification when readin conjunction with the appended drawings in which:

FIG. 1 discloses a representative embodiment of the invention, inperspective, with certain portions thereof broken away for clarity.

FIG. 2 is an enlarged view of a portion of the illustration of FIG. 1,and

FIG. 3 is a similar view showing a typical glue pattern for securingoverlapped margins of packaging material.

Referring now to the drawings, FIG. 1 shows a multi- Wall sack structureindicated by the reference numeral fabricated from kraft paper. The sackembraces four concentric tubes or sleeves 11, 12, 13 and 14 each havingoverlapped margins defining longitudinal lap seams 16, 17, 18 and 19,respectively.

The sack 10 forms an enclosure for receiving bulk material introducedthrough an opening 20 in Well known fashion.

The lap seams 16 through 19 are disposed longitudinally and are definedby overlapping margins secured together at spaced intervals as bygluing, stitching or heat sealing to provide a longitudinally disposedvent structure along each wall of the multi-Wall sack 10 defining aplurality of spaced joints 21-21 which are fixed against relativemotion. The seam further defines a plurality of intervening spaced gaps22--22 where the overlapped margins of packaging material are freelyseparable and susceptible of relative motion.

A typical longitudinal lap seam having vented structure in accordancewith the present invention is disclosed in FIG. 2 wherein overlappedmargins 23 and 24 are fixed relative to one another at spaced regions orpoints defined by the reference numerals 26-26 while the referencenumerals 27-27 define intervening points at which the overlapped margins23-24 are free to move relative to one another thus providing a conduitfor entrapped air from within a given wall structure.

FIG. 3 further shows a suitable pattern of glue indicated by thereference numerals 28-28 providing a longitudinal vent structure at thelap seam of a sack Wall fabricated of conventional kraft paper.

While the disclosed embodiment of the present invention embraces fourconcentric sacks, it is entirely Within the spirit and scope of theinvention that it take the form of a single Walled sack structure havingone or more longitudinal lap seams defining one or more longitudinalvents. Furthermore, it is intended that the invention may be practicedby utilizing any suitable packaging material such as plastic films,kraft paper and similar webs or sheets.

As a practical matter, it is probably most suitable to utilize at leasttwo concentric sacks developing at least one longitudinal vent in eachsack.

It is preferred that the vents be staggered as shown in FIG. 1 toprovide a tortuous path for the escape of air as the bulk materials areintroduced through the sack opening indicated by the reference numeral20.

Referring in more detail to FIG. 1, note that the broken line referencedM represents the instantaneous level of bulk material being continuouslyintroduced through the opening '20.

The feature to note is that while the individual vents or gaps 22-22 arenormally distended or opened when the bag is empty, by virtue of thenatural resilience of the paper, the vents tend to close automaticallyas the material M rises within the sack.

Note the condition of the openings 22-22 below the line referenced M asagainst the condition of the corresponding openings above line M.

Then vent seam operates as follows:

Prior to introduction of bulk material the sack is erected or inflatedto the condition shown in FIG. 1 by any suitable means. In thiscondition the vents 22-22 are generally in the condition shown above theline referenced M. As bulk material is introduced through the opening20, entrapped air within the sack 10 bleeds from the interior of thesack through the openings 22-22 in the lap seam of sack 14 thencethrough the corresponding openings in the sacks 13 and 12 until finallythe air vents to atmosphere through the openings 22-22 in the outer wall'11. As the level M of the bulk material progresses upwardly within thesack the internal pressure developed by the bulk material tends to drawthe vent seam taut to snap the vents 22-22 closed to retain the contentsof the sack.

It is anticipated that a variety of packaging materials may be utilizedand that -a great number of sack structures can be devised, includingthose embracing a single wall or a multi-w-all structure each with oneor more vent seams, without departing from the spirit and scope of thelongitudinal vent structure disclosed and claimed herein.

What is claimed is:

1. A vented sack for receiving and packaging bulk material such asflour, cement and the like comprising a body portion fabricated ofpackaging material having a generally tubular structure including alongitudinal lap seam, said lap seam having overlapped margins securedintermittently to provide spaced regions along said lap seam whereinsaid margins are fixed against relative motion with intervening spacedregions wherein the overlapped margins are freely separable andsusceptible of relative motion.

2. The vented sack structure as defined in claim 1 wherein the 'bodyportion is fabricated of a plurality of generally tubular structuresarranged concentrically and each having a longitudinal lap searncharacterized by overlapped margins secured intermittent-1y.

3. The vented sack structure as defined in claim 1 wherein the bodyportion is fabricated of a plurality of generally tubular structuresarranged concentrically, each tubular structure having a longitudinallap seam characterized by overlapped margins secured intermittently, thelap seam of each tubular structure being spaced from or staggeredrelative to the lap seam of the next adjacent wall.

4. In a multi-wall bag, a body portion of concentrically arranged pliesof material, each of said plies having overlapped margins defining alongitudinal seam, said margins being joined together at intermittentintervals to provide alternate gaps and joints, the longitudinal seamsof each ply being arranged in staggered relation so that no two adjacentseams are in overlapping relation.

5. The structure of claim 4 in which the gaps in adjacent seams arestaggered to define a tortuous path for air to escape as the bag isfilled.

6. A method of venting a multi-wall bag having a plurality of plies ofmaterial including the steps of, providing each of said plies withoverlapped margins defining a longitudinal seam, joining the overlappedmargins of each longitudinal seam at spaced intervals to providealternate joints and gaps, and staggering the seam of the plies so thatno two adjacent seams are in overlapping relation.

7. The method of claim 6 further including the step of staggering thegaps so that the gaps in adjacent plies are misaligned to provide atortuous path for air to escape as the bag is filled.

References Cited in the file of this patent UNITED STATES PATENTS

1. A VENTED SACK FOR RECEIVING AND PACKAGING BULK MATERIAL SUCH ASFLOUR, CEMENT AND THE LIKE COMPRISING A BODY PORTION FABRICATED OFPACKAGING MATERIAL HAVING A GENERALLY TUBULAR STRUCTURE INCLUDING ALONGITUDINAL LAP SEAM, SAID LAP SEAM HAVING OVERLAPPED MARGINS SECUREDINTERMITTENTLY TO PROVIDE SPACED REGIONS ALONG SAID LAP SEAM WHEREINSAID MARGINS ARE FIXED AGAINST RELATIVE MOTION WITH INTERVENING SPACEDREGIONS WHEREIN THE OVERLAPPED MARGINS ARE FREELY SEPARABLE ANDSUSCEPTIBLE OF RELATIVE MOTION.